1. Field of the Invention
This invention relates to the field of loudspeaker systems, and more particularly to a high efficiency, extended bass speaker enclosure.
2. Background Art
This inventor's U.S. Pat. No. 5,012,889 describes a speaker enclosure that provided a significant improvement over then state-of-the-art loudspeaker systems. One of the objects of my earlier invention was to provide a speaker system that yielded a lower or deeper response from a given-sized enclosure over conventional methods of tuning. Another object of my earlier invention was the elimination of various unwanted side effects of conventional tuning methods. For example, the loudspeaker enclosure described in my earlier patent avoided the creation of standing waves, which degrade the speaker's performance, by reducing parallel surfaces inside the speaker enclosure.
The interior of the enclosure was divided into two smaller chambers by means of a partition inclined with respect to the front and rear walls. One such chamber was adjacent to the speaker, while the second or rear chamber was separated from the front chamber by the partition. Below the speaker, a vent or port allowed the rear chamber to communicate with the environment outside of the enclosure.
Sound waves emanating from the rear of the speaker were reflected by the inclined partition toward the top of the speaker enclosure. The partition did not extend all the way to the top wall of the enclosure, thereby allowing sound waves to reflect off of the top wall and enter the rear chamber. The sound waves then exited the enclosure through the port below the speaker. The rear waves were thus delayed with respect to the front waves from the speaker to achieve the desired tuning of the speaker system. Furthermore, the arrangement of the interior partition caused the rear waves to be compressed at two locations thereby increasing the effective delay and further improving low frequency response.
Another embodiment of a speaker enclosure employing these design principles is described in my subsequently issued U.S. Pat. No. 5,111,905. The disclosures of both U.S. Pat. No. 5,012,889 and U.S. Pat. No. 5,111,905 are fully incorporated herein by reference.
Although the speaker enclosures of my earlier patents provided improved bass performance for a given-sized enclosure in comparison to other speaker designs of the time, it was found that reflected sound waves would effectively cancel some of the frequencies of sound and create non-linearities in the frequency response.